The aim of this research proposal is the development of gene therapy approaches to the treatment of AIDS based on the use of trans-dominant negative mutants of the HIV-1 regulatory protein Rev. Initially, we will attempt to optimize the trans-inhibitory properties of the rev mutants initially described by this laboratory by the phenotypic analysis of an extensive series of targeted mutations of rev. Subsequently, these mutants will be introduced into viral vector delivery systems suitable for infection of CD4+ T-cell lines, as well as primary human helper T-cells, primary human macrophages, and human hematopoietic stem-cell populations. At this stage, we intend to dedicate a significant effort to optimizing both the level of expression of the trans-dominants within the target cell populations as well as the achievement of viral vector titres sufficient for biological utility. In parallel, we will assess the ability of these viral vectors to protect various target cell populations against challenge by both cloned and primary isolates of HIV-1. If significant protection can be obtained in vitro using the derived viral vector systems, we intend to proceed, in collaboration with other laboratories that specialize in this area, to an initial test of in vivo efficacy using viral challenge to reconstituted SCID/Hu mouse chimeras. We believe that the experiments outlined in this proposal will allow a clear decision to be made on the eventual feasability of using trans-dominant variants of this HIV regulatory protein in the gene therapy of HIV infected individuals.